2 .\" "$Id: backend.man 7810 2008-07-29 01:11:15Z mike $"
4 .\" Backend man page for the Common UNIX Printing System (CUPS).
6 .\" Copyright 2007-2009 by Apple Inc.
7 .\" Copyright 1997-2006 by Easy Software Products.
9 .\" These coded instructions, statements, and computer programs are the
10 .\" property of Apple Inc. and are protected by Federal copyright
11 .\" law. Distribution and use rights are outlined in the file "LICENSE.txt"
12 .\" which should have been included with this file. If this file is
13 .\" file is missing or damaged, see the license at "http://www.cups.org/".
15 .TH backend 7 "CUPS" "12 May 2009" "Apple Inc."
18 backend \- cups backend transmission interfaces
24 job user title num-copies options [
29 Backends are a special type of \fIfilter(7)\fR which is used to
30 send print data to and discover different devices on the system.
33 Like filters, backends must be capable of reading from a filename
34 on the command-line or from the standard input, copying the
35 standard input to a temporary file as required by the physical
39 The command name (argv[0]) is set to the device URI of the destination printer.
40 Starting with CUPS 1.1.22, any authentication information in argv[0] is removed,
41 so backend developers are urged to use the DEVICE_URI environment variable
42 whenever authentication information is required. The CUPS API includes a
43 \fIcupsBackendDeviceURI\fR function for retrieving the correct device URI.
46 Back-channel data from the device should be relayed to the job
47 filters by writing to file descriptor 3. The CUPS API includes
48 the \fIcupsBackChannelWrite\fR function for this purpose.
51 When run with no arguments, the backend should list the devices
52 and schemes it supports or is advertising to stdout. The output
53 consists of zero or more lines consisting of any of the following
57 device-class scheme "Unknown" "device-info"
58 device-class device-uri "device-make-and-model" "device-info"
59 device-class device-uri "device-make-and-model" "device-info" "device-id"
60 device-class device-uri "device-make-and-model" "device-info" "device-id" "device-location"
64 The \fIdevice-class\fR field is one of the following values:
69 The device-uri refers to a specific direct-access device with no
70 options, such as a parallel, USB, or SCSI device.
75 The device-uri refers to a file on disk.
80 The device-uri refers to a networked device and conforms to the
81 general form for network URIs.
86 The device-uri refers to a serial device with configurable baud
87 rate and other options. If the device-uri contains a baud value,
88 it represents the maximum baud rate supported by the device.
91 The \fIscheme\fR field provides the URI scheme that is supported
92 by the backend. Backends should use this form only when the
93 backend supports any URI using that scheme. The \fIdevice-uri\fR
94 field specifies the full URI to use when communicating with the
98 The \fIdevice-make-and-model\fR field specifies the make and
99 model of the device, e.g. "Acme Foojet 2000". If the make and
100 model is not known, you must report "Unknown".
103 The \fIdevice-info\fR field specifies additional information
104 about the device. Typically this includes the make and model
105 along with the port number or network address, e.g. "Acme Foojet
109 The optional \fIdevice-id\fR field specifies the IEEE-1284 device
110 ID string for the device, which is used to select a matching
114 The optional \fIdevice-location\fR field specifies the physical location of
115 the device, which is often used to pre-populate the printer-location attribute
116 when adding a printer.
119 Backends without world execute permissions are run as the root
120 user. Otherwise, the backend is run using the unprivileged user
121 account, typically "lp".
124 The following exit codes are defined for backends; C API
125 constants defined in the <cups/backend.h> header file are defined
131 The print file was successfully transmitted to the device or
135 1 (CUPS_BACKEND_FAILED)
137 The print file was not successfully transmitted to the device or
138 remote server. The scheduler will respond to this by canceling
139 the job, retrying the job, or stopping the queue depending on the
140 state of the error-policy attribute.
143 2 (CUPS_BACKEND_AUTH_REQUIRED)
145 The print file was not successfully transmitted because valid
146 authentication information is required. The scheduler will
147 respond to this by holding the job and adding the
148 authentication-required job-reasons keyword.
151 3 (CUPS_BACKEND_HOLD)
153 The print file was not successfully transmitted because it cannot
154 be printed at this time. The scheduler will respond to this by
158 4 (CUPS_BACKEND_STOP)
160 The print file was not successfully transmitted because it cannot
161 be printed at this time. The scheduler will respond to this by
165 5 (CUPS_BACKEND_CANCEL)
167 The print file was not successfully transmitted because one or
168 more attributes are not supported. The scheduler will respond to
169 this by canceling the job.
172 All other exit code values are reserved.
175 \fIcupsd(8)\fR, \fIcupsd.conf(5)\fR, \fIfilter(7)\fR,
177 http://localhost:631/help
180 Copyright 2007-2009 by Apple Inc.
182 .\" End of "$Id: backend.man 7810 2008-07-29 01:11:15Z mike $".